I've barely hit 140k shit better not be wearing out. Have you done a compression test or anything.
LB7: lots of smoke and burning oil
- Thread starter OregonDMAX
- Start date
I've barely hit 140k shit better not be wearing out. Have you done a compression test or anything.
I am afraid to go into that are of the truck. A lot of rusty stuff down there thanks to road salt. I am afraid that I will be buying a lot of parts to do it. Maybe I should just stop being a sissy and try though...
scared that im going to need a motor if i go too much longer, with the low compression i have its only going to get worse.
do you only get smoke out of the breather and oil cap when warm? what about burning oil and/or dripping out of the breather?
and not to rub it in but i went to pull my glowplugs and they all came out smooth as butter with no PBblaster or anything. gotta love zero humidity dry climate, even winter here with snow is dry as hell.
do you only get smoke out of the breather and oil cap when warm? what about burning oil and/or dripping out of the breather?
and not to rub it in but i went to pull my glowplugs and they all came out smooth as butter with no PBblaster or anything. gotta love zero humidity dry climate, even winter here with snow is dry as hell.
It seems to do it more when it is warm. With the cold mornings it is always blowing smoke out the tailpipe due to the thick fuel. When it bothers me is when I am at a stop sign and it gets sucked into the cab by the blower fan. I took a piece of rubber hose and extended my breather tube just below the skid plate, about an inch and cut it at a 45 angle. There is always some 'oil sweat' at the tip and along that side of the engine, but very little dripping that I have noticed. I always look at that piece of steel that links the plugs together, looks like if I touched it, it would disintegrate!
I also have the same problem you do, I have not garage to get my truck into. I can only get it in up to the cab lights! We haven't had the snow, but we keep getting the cold, cold weather.
I also have the same problem you do, I have not garage to get my truck into. I can only get it in up to the cab lights! We haven't had the snow, but we keep getting the cold, cold weather.
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Sounds like we have the exact same thing going on by your description.
I will let you know what I check/ test and my results. Would at least give you a starting point. Either way your going to have to do a compression test to at least get a baseline. That was the first thing I was told to do and I was kinda shocked with the results.
I will let you know what I check/ test and my results. Would at least give you a starting point. Either way your going to have to do a compression test to at least get a baseline. That was the first thing I was told to do and I was kinda shocked with the results.
Hopefully your problem isn't anything serious, at 140k that would really suck.
At this point, before doing a leakdown test, I've narrowed it down to rings, valves/valve stem seals or something along those lines. I don't have any coolant consumption and rad hose is soft in the am. Its just oil/compression related.
This is kind of what I am thinking about doing. Was looking into glow plugs and that metal strap that connects them all. Stuff is usually so corroded and rusty on our trucks that I buy the parts that are likely to break during a project and then return them if I don't need them. Does anyone know if you NEED to use that metal strap to connect them? I was thinking of just making a harness with four leads coming off and connecting to the wire from the gp control module.
the straps are cheap i think i paid like $30 also there are many people selling motor parts you could easily get a set off another member.
my guess is they are needed because they are specifically bent in such a way and also coated.
also soak all of your glowplug threads with PBblaster every day for a week either before or after a good running on the motor.
my guess is they are needed because they are specifically bent in such a way and also coated.
also soak all of your glowplug threads with PBblaster every day for a week either before or after a good running on the motor.
Small update, got the cylinder leakdown test done and I have 10% leakage past all cylinders. Compression at 295-310 average.
So it looks like I will be doing rings at some point.
So it looks like I will be doing rings at some point.
I thought spec was anything under 25% was considered to be "okay"?
Well the compression is definitely not OK.
Cylinder leakage that exceeds 25 percent is considered excessive and may require component service. In excessive leakage situations, inspect for the following conditions.
Air leakage sounds at the intake manifold tube, may indicate a worn, stuck or burnt intake valve, broken valve spring, incorrect valve lash or damaged valve train components.
Air leakage sounds at the exhaust system tailpipe may indicate a worn, burnt, or stuck exhaust valve, broken valve spring, incorrect valve lash or damaged valve train components.
Air leakage sounds from the crankcase, oil level indicator tube, or oil fill tube may indicate worn piston rings, a damaged piston, a worn or scored cylinder bore, a damaged engine block or a damaged cylinder head.
Air bubbles in the cooling system may indicate a damaged cylinder head or gasket.
The only symptom you listed that I have is the excessive crankcase venting. Oil vapors and compression gasses.
You have a problem and did a leak test with only 10% found, right there in spec says anything more then 25% and its an issue. Your diagnosis may be wrong and the underlying issue is somewhere else. Just my .02 trying to help not argue.
I'm going off the compression numbers I got before the leakdown test. That with the crankcase pressure leads me to believe its rings. I could not get any leakage past valves or anything because it was all leaking past rings out crankcase.
Another update, not that it matters.
I took the truck to Performance Authority, home of "WhiteOut" and they did a leakdown test and the results were quite shocking... The cylinders with the worst compression were some of the cylinders with minimal leakage, about 5% or less. One of the highest compression cylinders had the worst leakage at 13%. Even though all cylinders were very low at around 295-305. Just doesn't make sense.
So at this point I'm just going to drive it until it blows up then, I can build the motor.
I took the truck to Performance Authority, home of "WhiteOut" and they did a leakdown test and the results were quite shocking... The cylinders with the worst compression were some of the cylinders with minimal leakage, about 5% or less. One of the highest compression cylinders had the worst leakage at 13%. Even though all cylinders were very low at around 295-305. Just doesn't make sense.
So at this point I'm just going to drive it until it blows up then, I can build the motor.
300psi is not very low, its actually the minimum compression listed by GM for the LB7 in the manual. The fact you have no variation across the cylinders is what is most important.
I don't know where the Duramax usually tests for cylinder leakage, as it is generally a very tight engine in my experiences, but in general the rule of thumb I've always heard is 10-20% being normal for a good street engine as long as you don't notice a lot of air escaping out of exhaust, intake etc.
How did the compression buildup when doing the compression test? If the rings are leaking it should be slow to buildup, but should still hit the peak pressure (300psi in your case). If the valves are leaking it should be very slow and not hit the peak, don't confuse this with a bent rod which will often build pressure fast like it should, just with a low peak pressure. Low meaning lower than the average of the other cylinders. I suspect a cracked piston would act like a leaking valve building pressure slowly and not hitting a peak. Not a common issue with the LB7 pistons though.
I don't know where the Duramax usually tests for cylinder leakage, as it is generally a very tight engine in my experiences, but in general the rule of thumb I've always heard is 10-20% being normal for a good street engine as long as you don't notice a lot of air escaping out of exhaust, intake etc.
How did the compression buildup when doing the compression test? If the rings are leaking it should be slow to buildup, but should still hit the peak pressure (300psi in your case). If the valves are leaking it should be very slow and not hit the peak, don't confuse this with a bent rod which will often build pressure fast like it should, just with a low peak pressure. Low meaning lower than the average of the other cylinders. I suspect a cracked piston would act like a leaking valve building pressure slowly and not hitting a peak. Not a common issue with the LB7 pistons though.
Some good points there actually. It builds compression fairly normal when testing. All the tests say the motor is fine or "not damaged" but the excessive smoke out of the breather and oil cap makes it look like it won't last another week.
As long as your fine running it until it blows or the mess is unbearable, then thats what I would do lol.